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Novel architectural features of Bordetella pertussis fimbrial subunit promoters and their activation by the global virulence regulator BvgA

Authors :
Qing Chen
Kimberly Baxter Decker
Philip E. Boucher
Scott Stibitz
Deborah M. Hinton
Source :
Molecular Microbiology. 77:1326-1340
Publication Year :
2010
Publisher :
Wiley, 2010.

Abstract

Summary A prominent feature of the promoters of Bordetella pertussis fimbrial subunit genes fim2, fim3 and fimX is the presence of a ‘C-stretch’, a monotonic run of C residues. The C-stretch renders these genes capable of phase variation, through spontaneous variations in its length. For each of these we determined the length of the C-stretch that gave maximal transcriptional activity, and found that the three optimized promoters align perfectly, with identical distances between conserved upstream sequences and the downstream −10 elements and transcriptional start sites. We also demonstrated, for Pfim3, that the conserved sequence corresponds to BvgA binding sites. The more upstream of the two binding sites is predicted to be high affinity, by comparison to a functionally derived consensus BvgA-binding sequence. The other binding site is a fairly poor match to this consensus, with 10 of 14 bp belonging to the C-stretch. Interestingly, the centre of this downstream site of BvgA binding coincides exactly with the centre of the expected typical location of a −35 sequence. However, the lack of a recognizable −35 element (CCCCCC versus TTGACA), and the occupation of this site by BvgA∼P suggest that activation of the fim promoters involves unusual interactions among BvgA, RNA polymerase and promoter DNA.

Details

ISSN :
0950382X
Volume :
77
Database :
OpenAIRE
Journal :
Molecular Microbiology
Accession number :
edsair.doi...........b29e11fc58503e8efb9dadc2b6f4942d
Full Text :
https://doi.org/10.1111/j.1365-2958.2010.07293.x